While reviewing the Sony A7R2 I have encountered several users who found out that when taking long exposures, the A7R II generates hot pixels. Now, is this problem real and will it affect your photography?
Yes it is real but only in certain circumstances.
Let’s say you are photographing the stars in a dark scene where you would like to see the stars and the non-lit landscape (or maybe only lit by the moon) in the final image. You can’t go slower than 25 sec because of star movement so you bump up the ISO to see something. So you choose an exposure where the stars and the shadows are still recoverable in the RAW in post.
And that’s where things get ugly. Bumping up the ISO or pushing the shadows in post make nasty little RGB buggers appear in your picture, which are very hard if not impossible to get rid of in post production.
I have taken pictures like this one for 12 minutes and I still had to bump up the exposure for far more than 2 EVs and I have never encountered any space invaders in my pictures. So yes the issue is very true and YES it can still be seen in Capture One.
WHAT NOW? IS THERE NOTHING WE CAN DO?
YES there is!
Turning on the Long Exposure NR (noise reduction) will get entirely rid of hot pixels, yay!
Yes that can be very annoying since the processing time of the images in-camera can be very long. (On the A7 it is as long as the exposure takes. So a 10 min exposure results in 10 min processing time).
BUT you will loose detail! Check out the image below.
If you are a Capture One user then import your image in there. In the details tab there is a magical Single Pixel slider that gets rid of about 60% of those. (The white ones and the colored ones).
You keep the detail.
NOW LET’S GET BACK TO REALITY
While the issue is there, in most cases, and especially in rightly exposed images and where there is light (and you do not need to push around the exposure in post) there is no need to worry. You can still see them though, but they are extremely hard to find at a 100% viewing scale.